Caster



FIG. 1 is a right side view of a caster showing my new design;

FIG. 2 is a left side view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a bottom view thereof;

FIG. 5 is a top paln view thereof;

FIG. 6 is an enlarged sectional view taken along line A--A of FIG. 1; and,

FIG. 7 is a back view thereof. 

The ornamental design for a caster, as shown and described. 